This invention relates to hay balers and, more particularly, to improvements associated with the clutch that activates the knotter and twine needles in such a baler.
U.S. Pat. No. 5,782,175 titled xe2x80x9cKnotter Clutch Control for Square Balersxe2x80x9d and assigned to the assignee of the present invention is directed to improvements that prevent the driven dog of the dog clutch on a baler from releasing to its actuated position for engagement with the driving lug of the clutch unless the lug is in a position where positive driving engagement between the lug and the dog is assured. The dog is normally maintained in its retracted position as the constantly moving sprocket having the driving lug mounted thereon rotates around the dog without making contact. The dog is held in the retracted position by a retainer that is released in response to the bale reaching a predetermined size, such release of the retainer permitting the dog to move out into its actuated position where it is picked up by the driving lug on the next cycle of revolution of the sprocket. A strategically located external lobe on the sprocket interacts with the retainer to prevent its release in the event the baler attempts to release the retainer when the lug is in the immediate vicinity of the dog, which release might cause the lug to only partially and temporarily catch the dog for driving the knotter through an operating cycle. By preventing the retainer from releasing unless the driving lug is spaced in its cycle from the dog, either on the approaching side or departing side thereof, positive interengagement between the lug and the dog can be achieved.
The external lobe also has the effect of resetting or tending to reset the retainer if the retainer has been released before the lobe reaches the reset roller. While this is of no particular consequence so long as the dog has been fully tripped and the operating lever associated therewith has moved past the retaining roller on the retainer, in some situations the roller may hang up on the tip of the lever as the external cam lobe tries to move the retainer in a resetting direction. Damage or breakage of components may result as the lobe attempts to swing the retainer inwardly at the same time the dog lever blocks such motion.
Accordingly, an important object of the present invention is to eliminate the potential for the retainer and dog to become jammed in a knotter clutch control of the type disclosed in the ""175 patent. Such jamming problem is avoided in the present invention by providing a degree of spring relief between the dog and the retainer such that, in the event jamming starts to occur, the spring relief permits relative movement between the two components in such a direction that one or the other of the components can continue its movement in the appropriate direction.
In a preferred embodiment, such relief is provided by having the dog-engaging part of the retainer spring-loaded so that it can yield when untoward binding forces attempt to arise between the retainer and the dog. Preferably, the dog-engaging part of the retainer takes the form of a swingable member having a relatively flat seat for the outer end of the dog lever, such member being yieldably biased by a tension spring into a dog-blocking position on the supporting body of the retainer.